An oxide semiconductor thin film transistor (TFT) refers to a TFT in which an active layer comprises an oxide semiconductor material. In the field of display, the oxide semiconductor TFT has been popular due to its advantages of a high mobility, a high uniformity, a transparent property, and a simple fabricating process for meeting requirements of a display device. The display device comprises a pixel area TFT and a gate driver on array (GOA) area TFT. The GOA area TFT is used to control signals input from a gate line. The GOA area TFT is subject to a significant forward bias, and is prone to a forward bias drifting which may lead to failure.